Modern commercial buildings are typically equipped with suspended grid supported ceiling systems. These ceiling systems conceal electrical conduit, air ducts and fire protection systems hung from a concrete ceiling/floor slab. In older buildings, asbestos was sprayed on the structure for fire protection.
FIG. 1 shows a portion of a typical suspended ceiling system comprised of light fixtures 10, acoustic ceiling panels 20 and supports 30. Each light is equipped with an adjustable lug 12 that spans a pair of supports 30. These supports 30 usually comprise angle iron suspended from wire 32 that is anchored to a metal or concrete structure (not shown). Support angle 30 is typically L-shaped to form a ledge 34 that supports the edge of ceiling panel 20. Support 30 can also be U-shaped or have an additional H, Z or T shaped member attached thereto. Light fixture lugs 12 are provided with screws 14 for adjusting the height of the fixtures. Screws 14 enable the bottom surface 22 of ceiling panel 20 to be flushed out with a lower lip 16 of the light fixture 10. A well known manufacturer of such ceiling systems was Soundlock Corporation of 2004 Breckenridge Drive N.E., Atlanta, Ga. 30345.
As noted above, in older buildings, a layer of asbestos insulation is often applied to the underside of the ceiling slab for fire protection purposes. This asbestos layer covers the underside of the slab and generally is applied after all necessary supports are anchored to the ceiling slab. The installation of new light fixtures or a new grid for the ceiling panel supports requires the removal of the asbestos layer.
Replacement or renovation of suspended ceilings is quite costly for buildings with asbestos insulation. Asbestos is carcinogenic and its removal is both time consuming and costly. Safety codes such as those provided by OSHA only allow workers to be exposed to a prescribed amount or area of asbestos at any given time. Therefore, large areas of floor space must be closed off for long periods of time during the removal process.
Ceiling panel replacement costs are further increased because existing light fixtures cannot be utilized. One reason for this is that extremely tight tolerances would have to be maintained during the manufacture of the ceiling panel in order to ensure proper fit and alignment with existing light fixtures. Another reason is that the old fixtures would be unsightly if left in place. The edges of these fixtures are generally worn, bent or rusted from years of use and the installation of new panels does not resolve this problem. New panels remain flush with the bottom surface of the lights and do not cover up the edges.
An additional problem associated with conventional suspended ceilings is that, over time, carcinogenic asbestos particles fall from the ceiling slab and accumulate on and penetrate the panels. This contaminates the panels and increases the likelihood that persons working in or occupying the building will be exposed to asbestos.
The present invention is provided to solve these and other problems.